Field of the Invention
The present invention relates to a hydraulic pressure supply system of an automatic transmission. More particularly, the present invention relates to a hydraulic pressure supply system of an automatic transmission capable of detecting a pressure exhausted from a high-pressure regulator valve to control an electric motor at an optimal revolution per minute (rpm).
Description of Related Art
Recently, as oil price has increased and exhaust gas emission regulations, or the like, have gradually been strengthened in the world, auto-makers are going-all out to develop a technology capable of improving fuel efficiency by an eco-friendly method.
Fuel efficiency in an automatic transmission may be improved by minimizing unnecessary consumption power of an oil pump.
As described above, in order to improve fuel efficiency, recently, an oil pump applied to automatic transmission is separately composed of a low-pressure oil pump and a high-pressure oil pump, such that hydraulic pressure generated in the low-pressure oil pump is supplied to a low-pressure part (a torque converter, a cooling part, a lubrication part), and hydraulic pressure generated in the high-pressure oil pump is supplied to a high-pressure part (a friction member selectively acting at the time of shifting).
That is, the automatic transmission including two oil pumps as described above is configured so that entire hydraulic pressure is generated based on the low-pressure part, and at the same time, only some of the hydraulic pressure is controlled to a high pressure required in the high-pressure part to thereby be supplied.
However, in a hydraulic pressure supply system according to the related art, since only whether or not a target pressure is reached is detected without detecting an excess flow, it is impossible to control the electric motor at an optimal RPM.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.